The Seattle Post-Intelligencer has a pretty good time line of how the global food crisis has developed:

Sept. 7, 2007: Vietnam, the world's third-biggest rice exporter, restricts rice exports to slow inflation.

Dec. 4: Argentina temporarily restricts grain exports.

Jan. 1: China, the world's biggest grain producer, starts to curb overseas sales of wheat, corn and rice by issuing export permits.

Jan. 19: Egypt bans rice exports.

Feb. 8: The American Bakers Association asks the U.S. Department of Agriculture to curb wheat exports.

Feb. 27: At least four people are killed during three days of protests over high commodity prices in Cameroon.

March: Philippines authorities begin to crack down on hoarders.

March 17: India halts all exports of non-basmati rice. It also extends an existing export ban on crops such as peas and beans.

March 28: Vietnam extends rice export restrictions.

April 4: Haitians riot over rising food prices. At least three people are killed.

April 6: Egyptians riot over rising food prices.

April 9: Corn commodities on the Chicago Board of Trade reach a record $6.16 a bushel.

April 12: Police clash with 10,000 workers in Bangladesh who smashed vehicles and attacked factories, demanding higher wages to pay for food.

The Haitian prime minister is forced to step down in an attempt to defuse anger over food prices. A U.N. police officer bringing food to his unit in Port-au-Prince is killed.

April 14: U.N. Secretary-General Ban Ki-moon says that a global food crisis has reached "emergency proportions." The World Bank has forecast that 33 nations from Mexico to Yemen may face social unrest.

April 16: Malawi plans to restrict corn exports.

April 17: Kazakhstan, the world's sixth-largest wheat exporter, bans wheat exports between April 27 and Sept.1.

April 18: India permits rice exports to Bhutan.

Indonesia, the world's third-largest rice producer, says it will hold back surplus rice.

April 22: Thailand, the world's largest rice exporter, is under pressure to restrict exports. A World Bank official likens any restriction to Saudi Arabia reducing oil exports.